The present invention generally relates to modeling methods and systems, and more particularly to modeling method and system for automatically designing an object model. An output obtained by the modeling method and system is used for making a design data base, used for generating data of a computer aided manufacturing (CAM), used in a computer aided design (CAD) for making drawings and the like.
The conventional modeling system can roughly be categorized into two types, one being the primitive instancing and the other being the geometrical modeling. According to the primitive instancing, an object model is described as a combination of primitives which are basic shapes so that the primitives do not overlap each other. The geometrical modeling includes the wire frame modeling which describes the object model by use of lines (wires), the face modeling which describes the object model by use of faces, and the solid modeling such as the constructive solid geometry and the boundary representation. According to the geometrical modeling, the basic shapes may overlap each other. For this reason, the degree of freedom with which the object model can be described by the geometrical modeling is considerably improved compared to that of the primitive instancing.
When automatically designing the object model, the degree of freedom of design is required both in the conceptual design in which the general shape and structure of the object model are defined and in the detailed design in which the dimensions of the object model are defined. However, the conventional modeling systems, that is, both the primitive instancing and the geometrical modeling, do not take into account the constituent elements of the object model. Various stages of deformation such as bending and cutting of a sheet metal, for example, cannot be described by the conventional method. In other words, the conventional modeling system does not take into account the material constituting the object model, and the burden is on the person making the design to take into account the material used when employing the geometric modeling, for example. This is because the geometric modeling designs the object model on the assumption that the material used is rigid and no deformation occurs. Since the geometric modeling does not take into account the material used, the automatically designed object model is nor necessarily realizable in actual practice.
Accordingly, the person making the design takes into account the material used when automatically designing the object model, but there is no way of accurately checking by a trial-and-error process how an actual completed model would look like because the person making the design simply assumes certain stages of the deformation of the material used based on his experience. Therefore, the conventional modeling systems suffer problems in that the application thereof is limited to the automatic design of an extremely simple object model in which the material used is neglected. That is, the conventional modeling systems merely give the geometrical description of the object model and not the functional description of the object model.
On the other hand, when entering data on a solid in the CAD system, for example, it is desirable that the data entry can be made efficiently. Conventionally, a coordinate input device such as a tablet is used to enter line segments of normal projections which describe the solid in two dimensions. The line segments entered from the coordinate input device are supplied to a data processing apparatus which analyzes the line segments in accordance with tables containing relationships of the line segments among the normal projections and generates data describing the solid in three dimensions. Such a system is proposed in a Japanese Laid-Open Patent Application No.61-60173, for example.
According to this proposed system, it is possible to more efficiently enter the data on the solid as compared to the case where the three-dimensional coordinates of the solid are directly entered manually from a keyboard or the like. However, when the configuration or structure of the solid is complex, there is a problem in that it takes an extremely long time to enter the line segments of the normal projections. Furthermore, there is also a problem in that it is extremely difficult to distinguish edges when the edges overlap each other in the normal projections. Therefore, from the practical point of view, the efficiency with which the data on the solid are entered still needs to be improved.